StemRoller: desktop stem separator, Android stems player, and server daemons

- stemroller/: PySide6/QML desktop app and player for separating music into stems
- android/: Plex music player that plays per-stem mixes, with Android Auto support,
  a graphic + parametric (Equalizer APO-style) EQ, and offline downloads
- server/: stemserve (serves stems to the app) and stemd (separates the library on
  the server's GPU, with "Stem Now" priority requests)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

stemroller/qml/StemRoller/StripedProgress.qml

@@ -0,0 +1,63 @@
+import QtQuick
+
+// Win7-style green-to-cyan striped bar. Backend sends <= 30 updates/s;
+// `shown` eases toward `value` and the stripes advance per frame by delta-time.
+Item {
+    id: root
+    property real value: 0
+    property bool active: true
+    property real shown: 0
+    property real phase: 0
+    property int barHeight: 6
+    implicitHeight: barHeight
+    readonly property int tile: barHeight * 2
+
+    onValueChanged: if (value < shown) shown = value
+
+    Rectangle {
+        anchors.fill: parent
+        radius: height / 2
+        color: Qt.rgba(1, 1, 1, 0.07)
+        border.color: Qt.rgba(1, 1, 1, 0.05)
+    }
+    Item {
+        id: fill
+        height: parent.height
+        width: Math.max(root.active ? root.barHeight * 2 : 0, parent.width * Math.min(1, root.shown))
+        clip: true
+        Rectangle {
+            anchors.fill: parent
+            radius: height / 2
+            gradient: Gradient {
+                orientation: Gradient.Horizontal
+                GradientStop { position: 0; color: Theme.success }
+                GradientStop { position: 1; color: Theme.accentGlow }
+            }
+        }
+        Image {
+            visible: root.active
+            x: -root.phase
+            width: parent.width + root.tile
+            height: parent.height
+            fillMode: Image.Tile
+            source: "image://fx/stripes/" + root.barHeight
+            cache: true
+        }
+        Rectangle {  // gloss
+            anchors { left: parent.left; right: parent.right; top: parent.top }
+            height: parent.height / 2
+            topLeftRadius: height
+            topRightRadius: height
+            color: Qt.rgba(1, 1, 1, 0.28)
+        }
+    }
+
+    FrameAnimation {
+        running: root.visible && (root.active || Math.abs(root.value - root.shown) > 0.0005)
+        onTriggered: {
+            root.shown += (root.value - root.shown) * (1 - Math.exp(-frameTime * 10))
+            if (root.active)
+                root.phase = (root.phase + frameTime * root.tile * 2.5) % root.tile
+        }
+    }
+}